I've lined a carrier and a payne up next to each other and they are identical. same parts, same warranty no real difference, at least not to label it the "garbage carrier brand". your paying for the name. bryant is the same too. haven't had much experience with Tempstar, they don't sell them around here. just looking at tempstar, they only offer a 10 year warranty on their high stuff, where as carrier, payne, bryant, trane, and american standard offer 10 year on everything (as long as you register). that would be a big thing when i'm choosing a brand.
we do not do a whole lot of residential, and don't sell specifically one manufacturer, when people ask me, i tell them, if your looking for inexpensive, Payne is a good furnace\ac with a good warranty. if you want higher end get a trane/american standard.